Hitwise recently published a rep report ort ("research note") that tracks holiday shopping trends and search market share, among several other things. The company found:
In the category it calls "search engines & directories sites," Google, Yahoo! and MSN accounted for approximately 73% of the total market share in November. It's not clear whether Hitwise includes all IYP sites (my assumption is yes; it lumps 1,700 sites into this category) but SuperPages was the only IYP to crack Hitwise's top 15.
Google sites had a net gain in traffic vs. Yahoo! Search and MSN Search ( Yahoo! and MSN have greater reach/traffic than Google in general).
Google had a 61.8% share of total search volume in November; Yahoo! Search and MSN Search had shares of 25.6% and 5.1%, respectively, (comScore and Nielsen's numbers aren't quite as dramatic).
The report suggests also that Google's momentum (and share growth in the past six months) is partly tied to the introduction of many new products/offerings.
Google's growth in market share appears to be confirmed (though at different levels) by all three major tracking firms, which is striking given the frenzy of competition in the search space. Next year will bring continuing competition and product innovation. Given the intensity of this year and the Hitwise data, it's hard to imagine anything in the immediate future to affect the balance of power in the general search space.
Local is more wide open and another thing all together—expect competition to only increase there too.